1. Field of the Invention
The present invention relates to textile structures comprising an organopolysiloxane-polyurea-(polyurethane) block copolymer and to the use of the block copolymer as a coating material or finishing material for fibers and textile fabrics.
2. Background Art
Polyurethanes are used inter alia as coatings for textile structures. Points of interest here include the protective effect and the water-repelling effect of the polyurethane coating. Polyurethanes are notable in this context for mechanical strength, elasticity, very good adhesion and abrasion resistance. However, polyurethanes also have distinct disadvantages, for example, absence of water vapor permeability, poor low-temperature performance, inadequate hydrolysis stability, high melt viscosities, and in some cases, nonexistent UV stability. Silicone elastomers, by contrast, possess excellent thermal, UV and weather stability, outstanding water vapor permeability and low melt viscosities, all without becoming brittle. They further possess water-repelling and nonstick surface properties. Moreover, coatings composed of crosslinked silicone elastomers have a distinctly more pleasant hand than, for example, polyurethane coatings. Unfortunately, the mechanical properties and the abrasion resistance of silicone elastomer coatings on textiles are inadequate for some applications such as highly stressed sportswear.
WO 00/64971 claims siloxane-containing polyurethane-urea polymers for use as textile fibers and in other applications. The polymers described therein have the common feature of very high moduli of elasticity (25-100 MPa) and breaking strengths (16-32 MPa) and therefore are classified as (impact-modified) thermoplastics. They are therefore proposed for use as a textile or shoe sole, as artificial leather, in membranes, etc.
In principle, the different property profiles of polyurethanes and silicones are very different and theoretically complement each other in an ideal manner. However, it is a matter of common experience that many desired property profiles are not achievable by means of mixtures of silicones and polyurethanes. In part as a result of the physicochemical incompatibility (miscibility, adhesion, reactivity, . . . ) of the components, attempts to combine the positive effects of the individual components by mixing the components together has lead to novel undesirable effects, while the original adverse properties of the individual components have generally persisted.
However, the preparation of urethane and silicone copolymers leads to siloxane-urethane block copolymers having good mechanical properties that are mechanically improved compared with the silicone homopolymers but continue to possess the positive properties of silicones. The combination of the advantages of the two systems thus leads to compounds having low glass transition temperatures, low surface energies, improved thermal and photochemical stabilities and a reduced tendency to hydrolyze. Such materials are described for example in EP 250248 A1 for use as pressure senstive adhesives, and EP 636361 A1 for use in cosmetics.
It has now been surprisingly discovered that textile properties are markedly improved by treating textile fibers or woven or non-woven fabrics with organopolysiloxane-polyurea-(polyurethane) block copolymers. Fibers and textiles treated with the block copolymers exhibit excellent hand, waterproofness, and water vapor permeability.